Event Title

Presenter Information

Location

Parker-Reed, SSWAC

Start Date

30-4-2015 2:00 PM

End Date

30-4-2015 3:55 PM

Project Type

Poster

Description

The hydrosphere during the Late Paleozoic Ice Age (LPIA) (roughly 360-300 million years ago: ma) reflects a dynamic coupling of high latitude ice sheets and global sea level. During the Pennsylvanian (326-298ma), sea-level fluctuations were mainly controlled by changes in global ice volume, which reflect a changing climate in the paleotropics. Evidence for glacial-eustatic control is documented in US Midcontinent cyclothems (alternating marine and nonmarine sedimentary depositional sequences), which record sea-level lowstands, transgressive and regressive sequences, and highstands. Due to the dynamic nature of the LPIA, far field (paleotropical) cyclothem deposits reflect the waxing and waning of predominantly large-scale Gondwanan continental ice sheets positioned in the southern hemisphere high latitudes. Fluctuations in sea level can be reliably inferred using ice volume modeling studies, physical relationships of anoxic sediments in the Late Paleozoic Midcontinent Sea, and variations in δ18O of marine fossils present in cyclothems. During the Pennsylvanian, glacial intervals (sea level lowstands) are characterized by anoxic marine bottom waters, coeval non-marine deposition (often paleosols), and higher δ18O values in vertebrate chordates (Conodonts). In contrast, interglacials (sea level highstands) are characterized by greater seawater circulation and primary productivity, marine and offshore deposits (often black/gray core shales), and lower δ18O values of marine species. This paper summarizes evidence for the extent, timing, and behavior of high latitude glaciers as reflected in the sea level record in the US Midcontinent.

Faculty Sponsor

Herb Wilson

Sponsoring Department

Colby College. Geology Dept.

CLAS Field of Study

Natural Sciences

Event Website

http://www.colby.edu/clas

ID

1453

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Apr 30th, 2:00 PMApr 30th, 3:55 PM

The Pennsylvanian Hydrosphere and Responses to Glacioeustasy

Parker-Reed, SSWAC

The hydrosphere during the Late Paleozoic Ice Age (LPIA) (roughly 360-300 million years ago: ma) reflects a dynamic coupling of high latitude ice sheets and global sea level. During the Pennsylvanian (326-298ma), sea-level fluctuations were mainly controlled by changes in global ice volume, which reflect a changing climate in the paleotropics. Evidence for glacial-eustatic control is documented in US Midcontinent cyclothems (alternating marine and nonmarine sedimentary depositional sequences), which record sea-level lowstands, transgressive and regressive sequences, and highstands. Due to the dynamic nature of the LPIA, far field (paleotropical) cyclothem deposits reflect the waxing and waning of predominantly large-scale Gondwanan continental ice sheets positioned in the southern hemisphere high latitudes. Fluctuations in sea level can be reliably inferred using ice volume modeling studies, physical relationships of anoxic sediments in the Late Paleozoic Midcontinent Sea, and variations in δ18O of marine fossils present in cyclothems. During the Pennsylvanian, glacial intervals (sea level lowstands) are characterized by anoxic marine bottom waters, coeval non-marine deposition (often paleosols), and higher δ18O values in vertebrate chordates (Conodonts). In contrast, interglacials (sea level highstands) are characterized by greater seawater circulation and primary productivity, marine and offshore deposits (often black/gray core shales), and lower δ18O values of marine species. This paper summarizes evidence for the extent, timing, and behavior of high latitude glaciers as reflected in the sea level record in the US Midcontinent.